Rebecca Adlington

If Rebecca Adlington can match the magical week she experienced in Beijing four years ago, the 23-year-old swimmer’s stock will rise to unbelievable heights. At the previous Olympics, Adlington became an overnight star after winning gold in the 400-m freestyle. A few days later, she set a world record in the heats of the 800-m freestyle before triumphing in the event — with another world record in the final, to boot. Expectations are understandably high, especially as Adlington is appearing in front of her fans, who will be desperately hoping she can replicate her achievements in the pool in China in 2008, when she became the first British swimmer in 100 years to win two Olympic gold medals. And having won gold at the 2011 World Championships (in the 800-m freestyle, for which she is the red-hot favorite in London) to go with a silver in the 400 m, she’ll be tough to knock off the Olympic podium.